It is not unusual, although most people did not bother to reregister. A great uncle and aunt of mine had a daughter born in 1917 before they married, and as my uncle was with the army in France at the time, the child was registered by my aunt under her own surname and with no mention of the father. The father of an illegitimate child had to be present before his name could appear on the certificate.
Twenty five years later, just before the daughter married, my uncle reregistered the birth with his own name and the date and place of the marriage. It probably took an event like a marriage or perhaps a child enrolling in a school to make folk look at their birth certificate and then think about reregistering.
